Size, it turns out, is not everything when it comes to insect vision. According to a new paper published this week in the Proceedings of the National Academy of Sciences, some of the smallest bees studied have photoreceptors as sharp as those of much larger honeybee drones.
The blue-banded bee Amegilla murrayensis. Image credit: Callin Switzer.
“The honeybee (Apis mellifera) — only one of the world’s roughly 20,000 bee species — has held a special place in vision research,” said lead author Dr. Elisa Rigosi of Lund University and colleagues.
“It is one of the best-studied insects, and much of what scientists know about how bees perceive the world is based on studies of honeybees.”
In the study, Dr. Rigosi and co-authors from Lund University and the University of Adelaide used a technique called intracellular recording to measure the electrical responses of individual photoreceptors — the light-sensing cells in an insect’s eye — in four bee species and both sexes of each.
The species included the buff-tailed bumblebee (Bombus terrestris), two related species in the Anthophorini tribe, and the solitary wool carder bee (Anthidium manicatum).
The researchers compared their results with previously published data on the honeybee.
Every group tested had sharper visual acuity than female honeybee foragers.
The most striking finding involved the blue-banded bee (Amegilla murrayensis), a small, solitary species from Australia.
Despite its modest eye size, it matched the ability of honeybee drones — bees specially adapted for high-speed aerial pursuit of queens — in detecting small, faint objects.
The scientists found that different species achieve strong vision through different anatomical strategies.
Male wool carder bees, which aggressively patrol and defend territories, invest heavily in densely packed, tightly focused visual sampling, at some cost to their ability to detect low-contrast objects.
Honeybee drones, by contrast, rely on unusually large lenses and light-collecting structures to maximize both sharpness and sensitivity at once.
The blue-banded bee achieves high performance more efficiently, apparently through low background noise in its visual cells rather than heavy structural investment.
“We were especially surprised that the small blue-banded bee could detect objects just as well as honey bee drones, despite being much smaller,” Dr. Rigosi said.
Source: Read the original article on www.sci.news
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